1. Field of the Invention
The present invention relates to a touch panel device. More specifically, the invention relates to the index matching touch panel device.
2. Description of Related Art
Touch panels are popular input devices. When the user touches a certain position on the touch panel, corresponding to the text or the images on the underneath display device, the touch panel senses the tactile signals and transmits them to a controller for further signal processing. The controller processes the tactile signals and outputs signals corresponding to the touched position. There are several types of touch panels, for example, resistive types, capacitive types, infrared types, surface acoustic wave types, etc. For instance, the capacitive touch panels detect the difference of capacitance of the touch panel. When the user touches the touch panel, the capacitor on the corresponding position is changed. The controller detects and calculates the difference of the capacitance and then outputs corresponding signals.
The conventional touch panel includes one or more layers of sensing electrodes, conductive circuits, masking elements, a supporting substrate, and a protective lens substrate providing anti-scratch, anti-glare, and/or anti-reflective function. The sensing layer, composed of transparent conductive material forming a plurality of pre-determined geometrical patterns, could sense the tactile signal. Suitable insulators are placed among those sensing electrodes to prevent false signal arising from the conductivity among the electrodes. However, if the refractive index of the sensing electrodes is different from the insulators or the supporting substrate, the visual effects of the screen behind the touch panel will be affected and the light transmission of touch panel will also be reduced. Therefore, a special structure and manufacturing method to reduce the visual difference and improve the visual effects of touch panel is required.